The present disclosure relates to a method and apparatus for applying abrasive grit, and more specifically to a method and apparatus for applying abrasive grit to gas turbine airfoils.
The efficiency of gas turbines is largely dependent on the effective sealing between the rotating components and the stationary components. One such location is between the radial end of the rotating airfoils and the outside walls of the compressor and the turbine sections. Tight clearances are highly desirable; however perturbations to the system caused by thermal growth of the components, foreign object ingestion, maneuvering of the aircraft, and others can cause an interference condition between the rotating and non-rotating parts.
One strategy to increase the robustness of the tight tolerance between the airfoil and the seal is to increase the wear resistance of the airfoil and decrease the wear resistance of the seal. Consequently, when the conditions exist for interference, the seal material is preferentially removed and the damage is locally limited.
One common approach for increasing the wear resistance of the airfoil is to attach abrasives to the airfoil tip. This effectively creates a “grinding” action that efficiently removes the seal material when there is interference. An electroplating process to attach abrasive grit requires application of a mask where plating is to be avoided. The mask is subsequently removed after the sequence of steps in the electroplating process is completed which is a relatively time consuming and costly process.
Although effective, the electroplating process to attach cubic Boron Nitride (cBN) abrasives is relatively slow, capital intensive, and requires multiple operations including time consuming masking.